Multiple-roll supercalender



C.SCHURIV1ANN.

MULTIPLE ROLL-SUPERCALENDER.

APPLICATION man AUG. 29, 1921.

Patented July 25, 1922.

Eyed

figi

I J wejziar 1 A urr srTris IEHCE.

CARL soirtiaamnn, or Dus sELDoRr, GERMANY.

MULTIPLE-ROLL SUPERCALENDIPR.

Specification of Letters Batent;

Patented J iii 25, 115E273.

Application filed August 29, 1921, Serial No. 496,686.

1 0 all w from i 6 may concern i I Be it known that I, CARL SGHI'FRMANN,a citizen of the German Republic, and residing at Dusseldorf, Germany,have invented cerby an upper anda lower hard roller. This has thefollowing drawbacks.

The hard rolls mentioned are, in consequence of their necessarythickness both heavy and expensive. Owing to the difficulty in theirmanufacture and their tedious machining they require a long term fordelivery, in particular if the casting should prove faulty, whatfrequently only appears towards the end of the machining process, sothat the delivery of the whole super-calen dcr is thereby delayed.

hen, as in most cases, the journals are cast in one piece with the rolland are not made as separate steel trunnions or a steel shaft pressedthrough the roll, they have to be made of a comparatively largediameter, so as to render them proof against breaking, whereby-thefrictional moment in the hearing is unnecessarily increased, inparticular in the lowest roll.

Between the terminal hard rolls. alternately elastic rolls made ofpaper, cotton or the like and thin, non-elastic rolls (chill cast rolls)are disposed. The number of the latter determines the maximum speed andthe calendering effect of the calender, as only the contact pointsbetween elastic and hard rolls have a smoothing eifect which is thegreater, the thinner the hard rolls are, because. at a constant pressurethe surface pressure between the elastic rolls and the hard rolls willincrease with a decrease in the diameter of the hard rolls. The passagesbetween the lowest and the uppermost pairs of rolls are, therefore, withthe heretofore constructed super-calenders are, owing to the largediameter of the terminal hard rolls not as effective as the others.

The terminal hard rolls are, by taking up the total pressure, caused tosag, and this sagging is communicated tothe neighboring, elastic (paperor cotton) roll, as the latter will, after a short time, adapt itself tothe harder roll. Thesagged hard roll, therefore, rounds the paper rollabove it,

the neat hard roll, however, tends to force.

the same paper roll into a concave form. The shell of the paper roll is,therefore, at each half revolution, subje'ctedto adeformation; If,however, the lowest hard roll is made with a rounded surface, so that,at

a given load, it will line up straight against the-paper roll above it,the surface of contact' will, at a different load, no more berectilinear. I I I It is, now, the objectof the present inventiontoobviate the drawbacks mentioned by means of a novel arrangement of therolls.

In the accompanying drawing Fig. 1 shows the heretofore employedarrangement of rolls in side elevation, Fig. 1 only the lower part ofthe same in front elevation, Figs. 2 and 2 respectively, are thecorresponding views of the new arrangement of the rolls, which has thefollowing essential features:

1. For the terminal. hard rolls at the top or bottom, or preferably bothat top and bottom, are substituted elastic (paper or cotton) rolls witha steel shaft through them.

The drive of the calender has, in consequence, been shifted from thelowermost or third. roll to the second or seventh roll from below.

The total number of hard rolls has been reduced by 1, that of theelastic rolls been increased by 1. Therefore, obviously, also the numberof hard roll scrapers is reduced by 1, and the total height of thecalender is, at the same diameter of the rolls, reduced by thedifference between the diameter of a medium sized paper roll and a thinhard roll. I

4. The smoothing points, which remain of the same number, lie onlybetween thin hard rolls and elastic rolls and. therefore, produce amaximum effect. If the rolls are, at the same time, slightly staggeredas shown in Fig. 2 and described in the German Patent specification No.252,151, the diameters of the middle hard rolls and paper rolls may bereduced to their practically smallest size, as the danger of theiryielding sideways is removed.

If, with this new arrangement, thelowest paper roll should inconsequence of the weight resting upon it, sag it will be pressed by thethin hard roll above it, most at its two ends. Contrary to theheretofore arrangement the lowermost, elastic roll (Fig. 2 has to adaptitself to the cylind'ricat hard roll above it, and it will have toassume after a short time a rounded form, which corresponds to its load,so that it will, along its whole length, bear evenly against the thinhard roll. In case the load should vary, the rounding will change byitself correspondingly. The strength of a roll pressed of paper orcotton with a steel shaft through it against sagging greater than mayappear at the first moment. Not only the section of the steel shaft willhere come into, question, but also that part of the paper shell sectionwhich, in case of such sagging is subjected to a compressing strain. S0,

for example, the strength of a paper roll, the shaftdiameter is equalto, one half of the outside diameter of the roll, will be about threetimes as great as the strength of the inner shaft alone. A tightlycompressed paper or cotton roll therefore, verywell adapted asterminalroll in a cale der, already alone forthe reason that its journals aremade in one piece with the inner steel shaft.

The drive of the new calender (Fig. 2)

is effected always from a thin hard roll. For this, obviously the secondor 4th roll may. according to the total number of rolls employed, bechosen. When the Lth roll is driven, it will be found advisable to drivefrom it also the second roll from below with a small lead, so that thetension pro duccd in the upper passages will not too suddenly disappearin the paper web and thereby cause the latter to tear at the drivenroll.

I claim:

1. In a multiple roll calender an elastic terminal roll disposed belowor at the top, or both below and at the top.

2. In a multiple roll calender with elastic rolls below and at the top,the drive effected from the second or fourth roll from below.

In a multiple roll calender with elastic rolls at the top and bottom,the drive eifected from the fourth roll from below, and the second rollfrom below again driven from said fourth roll.

In testimony whereof I afiix mysignature in presence of two witnesses.

CAR SCHURMANN.

Emit; BaUcERT.

